Topic: Mutualism

Target group

8th‑grade students of elementary school

Core curriculum

General requirements

I. Knowledge of biological diversity and basic biological phenomena and processes. Pupil:

3. presents and explains the relationship between the organism and the environment.

Specific requirements

VII. Ecology and environmental protection. Pupil:

4. analyzes non‑antagonistic interactions: obligatory mutualism (symbiosis), facultative mutualism (protoccooperation) and commensalism.

General aim of education

You will learn what mutualism is about

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• explain what symbiosis and mutualism are and give them examples;

• explain that symbiosis is the result of adaptation to the environment.

Methods/techniques

• activating

  • discussion.

• expository

  • talk.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers.

Lesson plan overview

Before classes

• Students get acquainted with the content of the abstract. They prepare to work on the lesson in such a way to be able to summarize the material read in their own words and solve the tasks themselves.

Introduction

• The teacher explains the aim of the lesson and together with students determines the success criteria to be achieved.

• Then he writes the subject of the lesson on the blackboard or interactive whiteboard. Students write it in notebooks..

• Students interpret the cover illustration, indicating its relationship with the subject and goals of the lesson.

Realization

• The teacher asks students to read the abstract themselves, paying particular attention to the illustrations.

• The lecturer presents an interactive illustration of „The universality of non‑antagonistic relations in nature”. On the basis of it and on the basis of the resources from the lesson „Mutualism” in the e‑textbook explains such terms as: non‑antagonistic relations, symbiosis, mutualism, mycorrhiza, simultaneously informing that non‑antagonistic relations are very common in nature, although not always noticeable at first glance ..

• The teacher divides the class into groups. The task of each group is to conduct a detailed analysis of another case of mutualism, from the examples described in the abstract. An example to analyze can be assigned to each group by the teacher or students can draw it from the available pool..

• Students carry out the interactive exercises checking the level of knowledge learned during the lesson. The teacher initiates a discussion during which the correct solutions for all the exercises performed by the students are discussed.

Summary

• At the end of the lesson the teacher asks: If there was going to be a test on the material we have covered today, what questions do you think would you have to answer? If the students do not manage to name all the most important questions, the teacher may complement their suggestions.

Homework

• Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

• Develop a lap book containing issues learned during the lesson and bring your work to the next class.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Mutualism

Many species of animals, plants and fungi coexist and cooperate with other species, which is generally beneficial to both organisms. This type of relation is called symbiosis and belongs to a group of non‑antagonistic relations. A kind of symbiosis in which cooperation between two species is necessary for their survival is referred to as mutualism, i.e. obligatory symbiosis. An example of this type of symbiosis is the cooperation of fungi and green algae forming lichens. Lichens are found in extremely unfavorable conditions, in which the living components of lichen could not survive. The fungus protects the algae cells against negative impact and absorbs water from the environment, and the algae conducts photosynthesis to produce nutrients for itself and its partner. They even reproduce together. They form easily detachable clusters of fungus and algae cells (isidia or soredia) that spread by the wind inhabit new environment.

A very interesting case of symbiosis is the relationship between manioc ants, living in Middle and South America, and fungi. These ants are not able to feed on the leaves, because they do not digest the cellulose contained therein. Therefore, they prepare the surface from them, instil fungi thereon and cultivate them. The cultivated fungi form at the ends of their hyphae spherical construct filled with easily digestible substances from the substrate decomposed by the fungi, which the ants collect and feed on. In the wilderness, there are no manioc ants in nests without fungi, and these fungi can be found only in the nests of manioc ants.

A special case of mutualism is the symbiotic relationship between ruminants, such as cows or deer, and microorganisms living in their digestive systems. In one of the parts of their multi‑chambered stomach, called the rumen, live bacteria and protozoa capable of digesting cellulose. From time to time, rumen content, partially digested by symbionts, returns to the mouth of the animal, where it is masticated. When swallowed again, grass and certain microorganisms are digested with the help of herbivore's digestive enzymes. This way, ruminants gain not only sugars but also protein and vitamins (mainly vitamins from B group and vitamin K) produced by bacteria.

Another example of symbiosis is the relationship between flowers and their pollinators. This is how the flowers can transfer male gametes from one flower (specimen) to another. As a result, fertilisation and seed production occurs. In return, pollinators use the nectar and pollen produced by flowers. In the case of certain plant species, only one specially adapted insect species can pollinate them. This is the case of red clover. It has particularly long and narrow flowers, the bottom of which can only be reached by the mouthpiece of a bumblebee. Clover cannot exist without this insect, but the bumblebee can also feed on the nectar of other flowers. Hummingbirds are also specialists in pollination of specific species. They only visit those flowers whose shape fits perfectly the shape of their beaks.

Mycorrhiza, cooperation of fungi with plants, is also a case of mutualism. It involves braiding the roots of a plant by the hyphae of the mycelium, which grow into their interior, and form a dense network on their surface. Mycelium increases the absorbent surface of the root. This way, the fungi take and supply water, phosphorus and nitrogen compounds to the plants. In exchange, they can feed on the nutrients produced by plants in the process of photosynthesis. Larch seeds, as they fall on the soil overgrown with mycelium of the suillus luteus, quickly sprout and develop healthy plants. A larch grows much weaker in soil deprived of mycelium.

Further pairs of species that provide services to one another are birch boletes and birches, porcini mushrooms and oaks, red pine mushrooms and spruce.

• Non‑antagonistic relations bring benefits to at least one of the parties.

• Symbiosis is a way to adapt to the environment.

• Species living with each other in symbiosis usually develop adjustments that allow them to remain in this relationship that are reflected , e.g. in their physique.